Strontium and cesium release mechanisms during unsaturated flow through waste-weathered Hanford sediments

Hyun Shik Chang, Wooyong Um, Kenton Rod, R. Jeff Serne, Aaron Thompson, Nicolas Perdrial, Carl I. Steefel, Jon Chorover

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Leaching behavior of Sr and Cs in the vadose zone of Hanford site (Washington) was studied with laboratory-weathered sediments mimicking realistic conditions beneath the leaking radioactive waste storage tanks. Unsaturated column leaching experiments were conducted using background Hanford pore water focused on first 200 pore volumes. The weathered sediments were prepared by 6 months reaction with a synthetic Hanford tank waste leachate containing Sr and Cs (10 -5 and 10 -3 molal representative of LO- and HI-sediment, respectively) as surrogates for 90Sr and 137Cs. The mineral composition of the weathered sediments showed that zeolite (chabazite-type) and feldspathoid (sodalite-type) were the major byproducts but different contents depending on the weathering conditions. Reactive transport modeling indicated that Cs leaching was controlled by ion-exchange, while Sr release was affected primarily by dissolution of the secondary minerals. The later release of K, Al, and Si from the HI-column indicated the additional dissolution of a more crystalline mineral (cancrinite-type). A two-site ion-exchange model successfully simulated the Cs release from the LO-column. However, a three-site ion-exchange model was needed for the HI-column. The study implied that the weathering conditions greatly impact the speciation of the secondary minerals and leaching behavior of sequestrated Sr and Cs.

Original languageEnglish (US)
Pages (from-to)8313-8320
Number of pages8
JournalEnvironmental Science and Technology
Volume45
Issue number19
DOIs
StatePublished - Oct 1 2011

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Cesium
Strontium
unsaturated flow
cesium
strontium
Leaching
Minerals
Sediments
leaching
ion exchange
Ion exchange
secondary mineral
Weathering
sediment
Radioactive waste storage
Dissolution
weathering
dissolution
cancrinite
chabazite

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry

Cite this

Strontium and cesium release mechanisms during unsaturated flow through waste-weathered Hanford sediments. / Chang, Hyun Shik; Um, Wooyong; Rod, Kenton; Serne, R. Jeff; Thompson, Aaron; Perdrial, Nicolas; Steefel, Carl I.; Chorover, Jon.

In: Environmental Science and Technology, Vol. 45, No. 19, 01.10.2011, p. 8313-8320.

Research output: Contribution to journalArticle

Chang, Hyun Shik ; Um, Wooyong ; Rod, Kenton ; Serne, R. Jeff ; Thompson, Aaron ; Perdrial, Nicolas ; Steefel, Carl I. ; Chorover, Jon. / Strontium and cesium release mechanisms during unsaturated flow through waste-weathered Hanford sediments. In: Environmental Science and Technology. 2011 ; Vol. 45, No. 19. pp. 8313-8320.
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